Pork carcasses are typically cut into six initial portions, including the left and right front and hind quarters, and the left and right middles. The loin is part of the middle portion, adjacent the backbone in between the ribs and outer layer of back fat.
The conventional loin puller machine, which separates the loin from the carcass middle, has been substantially unchanged for approximately twenty years. One example of a prior art loin puller is from Acraloc, in Tennesee, as described in their U.S. Pat. No. 5,882,252.
A typical loin puller can process 1,300 pork middles per hour. Cutting accuracy is critical. For example, if a scribe saw cuts into the rib bone then the primary meat cutting blade cuts through the bone more than one-quarter inch into the belly underneath. That part or the belly, which later becomes bacon, then falls off causing yield loss. If the scribe saw cut is too shallow, when the meat cutting blade tries to pass through the scribe saw blade path, without the bone being cut all the way through. This partial bone cut results in major bone damage, with chips of broken bone distributed throughout the meat.
The pork processing industry has had several long standing problems with conventional loin pullers. In a conventional loin puller, a rotary scribe saw is provided with a ski fixed to the head or standard. The depth of the scribe saw blade cut is controlled by a mutable part system. This system includes a wheel which rides on top of the rib, so as to create a counter resistance to the air cylinder that also brings the scribe saw downward into the rib bone. This air regulation of the cutting depth is inconsistent due to temperature variations in the carcass. A problem arises since the meat product temperature changes throughout the day. Soft product will cause the depth control wheel to sink in, letting the sscribe saw blade cut too deep. With hard product, the wheel rides on top, with no “give,” causing the scribe saw blade to not cut all the way through. Also, the fixed ski on the scribe saw standard limits sharping of scribe saw blade, and thus shortens the life of the blade.
The scribe saw blade on a conventional loin puller is also subject to wear and failure due to loads on the drive shaft. Since the blade operates at approximately 2,000 RPM, wear damage can occur quickly, leading to breakage of the blade. Such excessive wear can be the result of a side load on the drive gear shaft, which deflects the shaft and thereby deflects the blade, which then rubs on the standard. Breakage of the blade is a significant safety hazard.
Another problem with the conventional loin puller is wear and damage to the various shafts. The pinion shaft is connected to a motor drive shaft via a single keyway, which generates pressure on only one side of the motor shaft, which can lead to complete failure of the motor shaft. Also, because the ball bearing between the pinion shaft and motor shaft has very limited contact only at the point where the ball is touching the shafts, the longevity of the bearing, motor shaft, and pinion shaft is compromised.
Conventional loin pullers are also known to lose the mount bolts which mount the scribe saw standard to the motor. The side loads on the assembly tend to loosen the mounting bolts, which can then become lost in the meat product.
The single bearing use in a conventional loin puller also causes the ring or bevel gear and pinion gear to misalign due to flexing, thereby leading excessive wear and breakage of the shafts and/or the scribe saw blade.
Therefore, a primary objective of the present invention is the provision of an improved loin puller scribe saw assembly which overcomes the problems of the prior art.
Another objective of the present invention is the provision of a loin puller scribe saw assembly having an adjustable ski for controlling the depth of the scribe saw cut.
A further objective of the present invention is the provision of a scribe saw assembly for a loin puller having improved bearings to minimize wear and damage, and to increase life of the assembly components.
Still another objective of the present invention is the provision of a scribe saw assembly for a loin puller having load bearing pins to reduce or eliminate transfer of operational loads.
Yet another objective of the present invention is the provision of a loin puller scribe saw assembly having a pinion shaft with a double keyway to enhance tightening of the pinion to the pinion shaft and to equalize pressure on both sides of the motor shaft.
A further objective of the present invention is the provision of a scribe saw assembly for a loin puller which reduces wear and minimizes risk of shaft or blade damage.
Another objective of the present invention is the provision of a scribe saw assembly for a loin puller which increases the life expectancy of the scribe saw blade and other components.
Still another objective of the present invention is the provision of a scribe saw assembly having a machined or cast standard with high tolerances, and with a smoother finish to provide easier cleaning and less bacteria traps.
Another objective of the present invention is the provision of a scribe saw assembly for a loin puller which is economical to manufacture, and simple, safe and durable in use.
These and other objectives become apparent from the following description of the invention.